/*
 *
 *  * Copyright 2015 Skymind,Inc.
 *  *
 *  *    Licensed under the Apache License, Version 2.0 (the "License");
 *  *    you may not use this file except in compliance with the License.
 *  *    You may obtain a copy of the License at
 *  *
 *  *        http://www.apache.org/licenses/LICENSE-2.0
 *  *
 *  *    Unless required by applicable law or agreed to in writing, software
 *  *    distributed under the License is distributed on an "AS IS" BASIS,
 *  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  *    See the License for the specific language governing permissions and
 *  *    limitations under the License.
 *
 *
 */

package org.nd4j.linalg.api.rng;

import org.nd4j.linalg.api.ndarray.INDArray;

/**
 * Random generation based on commons math.
 * This is mean to be an independent.
 *
 * @author Adam Gibson
 */
public interface Random {

    /**
     * Sets the seed of the underlying random number generator using an
     * <code>int</code> seed.
     * <p>Sequences of values generated starting with the same seeds
     * should be identical.
     * </p>
     *
     * @param seed the seed value
     */
    void setSeed(int seed);

    /**
     * Sets the seed of the underlying random number generator using an
     * <code>int</code> seed.
     * <p>Sequences of values generated starting with the same seeds
     * should be identical.
     * </p>
     *
     * @param seed the seed value
     */
    void setSeed(int[] seed);


    /**
     * Sets the seed of the underlying random number generator using a
     * <code>long</code> seed.
     * <p>Sequences of values generated starting with the same seeds
     * should be identical.
     * </p>
     *
     * @param seed the seed value
     */
    void setSeed(long seed);

    /**
     * Gets the  <code>long</code> seed of the underlying
     * random number generator.
     *
     * @return the seed value
     */
    long getSeed();

    /**
     * Generates random bytes and places them into a user-supplied
     * byte array.  The number of random bytes produced is equal to
     * the length of the byte array.
     *
     * @param bytes the non-null byte array in which to put the
     *              random bytes
     */
    void nextBytes(byte[] bytes);

    /**
     * Returns the next pseudorandom, uniformly distributed <code>int</code>
     * value from this random number generator's sequence.
     * All 2<font size="-1"><sup>32</sup></font> possible <tt>int</tt> values
     * should be produced with  (approximately) equal probability.
     *
     * @return the next pseudorandom, uniformly distributed <code>int</code>
     * value from this random number generator's sequence
     */
    int nextInt();

    /**
     * Returns a pseudorandom, uniformly distributed <tt>int</tt> value
     * between 0 (inclusive) and the specified value (exclusive), drawn from
     * this random number generator's sequence.
     *
     * @param n the bound on the random number to be returned.  Must be
     *          positive.
     * @return a pseudorandom, uniformly distributed <tt>int</tt>
     * value between 0 (inclusive) and n (exclusive).
     * @throws IllegalArgumentException if n is not positive.
     */
    int nextInt(int n);

    /**
     * Returns the next pseudorandom, uniformly distributed <code>long</code>
     * value from this random number generator's sequence.  All
     * 2<font size="-1"><sup>64</sup></font> possible <tt>long</tt> values
     * should be produced with (approximately) equal probability.
     *
     * @return the next pseudorandom, uniformly distributed <code>long</code>
     * value from this random number generator's sequence
     */
    long nextLong();

    /**
     * Returns the next pseudorandom, uniformly distributed
     * <code>boolean</code> value from this random number generator's
     * sequence.
     *
     * @return the next pseudorandom, uniformly distributed
     * <code>boolean</code> value from this random number generator's
     * sequence
     */
    boolean nextBoolean();

    /**
     * Returns the next pseudorandom, uniformly distributed <code>float</code>
     * value between <code>0.0</code> and <code>1.0</code> from this random
     * number generator's sequence.
     *
     * @return the next pseudorandom, uniformly distributed <code>float</code>
     * value between <code>0.0</code> and <code>1.0</code> from this
     * random number generator's sequence
     */
    float nextFloat();

    /**
     * Returns the next pseudorandom, uniformly distributed
     * <code>double</code> value between <code>0.0</code> and
     * <code>1.0</code> from this random number generator's sequence.
     *
     * @return the next pseudorandom, uniformly distributed
     * <code>double</code> value between <code>0.0</code> and
     * <code>1.0</code> from this random number generator's sequence
     */
    double nextDouble();

    /**
     * Returns the next pseudorandom, Gaussian ("normally") distributed
     * <code>double</code> value with mean <code>0.0</code> and standard
     * deviation <code>1.0</code> from this random number generator's sequence.
     *
     * @return the next pseudorandom, Gaussian ("normally") distributed
     * <code>double</code> value with mean <code>0.0</code> and
     * standard deviation <code>1.0</code> from this random number
     * generator's sequence
     */
    double nextGaussian();

    /**
     * Generate a gaussian number ndarray
     * of the specified shape
     *
     * @param shape the shape to generate
     * @return the generated gaussian numbers
     */
    INDArray nextGaussian(int[] shape);

    /**
     * Generate a gaussian number ndarray
     * of the specified shape and order
     *
     * @param order the order of the output array
     * @param shape the shape to generate
     * @return the generated gaussian numbers
     */
    INDArray nextGaussian(char order, int[] shape);

    /**
     * Generate a uniform number ndarray
     * of the specified shape
     *
     * @param shape the shape to generate
     * @return the generated gaussian numbers
     */
    INDArray nextDouble(int[] shape);

    /**
     * Generate a uniform number ndarray
     * of the specified shape and order
     *
     * @param order order of the output array
     * @param shape the shape to generate
     * @return the generated gaussian numbers
     */
    INDArray nextDouble(char order, int[] shape);

    /**
     * Generate a gaussian number ndarray
     * of the specified shape
     *
     * @param shape the shape to generate
     * @return the generated gaussian numbers
     */
    INDArray nextFloat(int[] shape);

    /**
     * Generate a random set of integers
     * of the specified shape. Note that
     * these integers will not actually be integers
     * but floats that happen to be whole numbers.
     * The reason for this is due to ints
     * having the same space usage as floats.
     * This also plays nice with blas.
     * <p/>
     * If the data type is set to double,
     * then these will be whole doubles.
     *
     * @param shape the shape to generate
     * @return the ndarray with
     * the shape of only integers.
     */
    INDArray nextInt(int[] shape);


    /**
     * Generate a random set of integers
     * of the specified shape. Note that
     * these integers will not actually be integers
     * but floats that happen to be whole numbers.
     * The reason for this is due to ints
     * having the same space usage as floats.
     * This also plays nice with blas.
     * <p/>
     * If the data type is set to double,
     * then these will be whole doubles.
     *
     * @param shape the shape to generate
     * @param n     the max number to generate trod a
     * @return the ndarray with
     * the shape of only integers.
     */
    INDArray nextInt(int n, int[] shape);

}


